There's a problem with your google maps (main page, listing all onsen) locations for Asahi yu and Sundan no yu. They should be in Hokkaido, but the map shows them being on Kyushu, in Beppu.

Edit: and Niwa no Yu, which should be in Gunma, is shown being somewhere near Yufuin

Hi slycker,

Thanks for the message. Indeed, most of the onsen were wrongly located on the Secret Onsen web site at www.secret-japan.com/onsen, due to a small problem when the data file was updated.

It was corrected

sanji